Our block is very flat and we have a corner (south-west) of the property that has the issues of traffic noise, dust, wind and turning car lights coming in through our windows (it's a great corner!). Anyway my idea is to get in some fill and create an earth berm (or series of mounds), possibly a couple of metres high and I thought if I was going to that sort of trouble I might be able to incorporate something like an earth cellar (a little hobbit hole) for storing things 'underground'.

I'm wondering if anyone has ever designed a root cellar or anything like this? And if anyone has any advice or comments on the idea. Do you know of any design books, websites etc. that might have something similar?

Maybe an old mini mix concrete mixer, like on the smaller concrete trucks, that way you have a nice round hole that will outlast you. Just a thought. Talk to metal recyclers who might have some cool box or thing that suits what you want to do, and it should be pretty cheap.

Excellent, thanks. The concrete mixer drum also made me think of the people around here who sell old shipping containers. That might be worth consideration too but I guess it will depend on how much they want for them. I'll check the book out too.

A large barrel, set on it's side could be useful. Covered with the berm, a nice door attached, etc. What about ventilation?

Another way could be to fill sandbags with soil and stack them to form the size/shape you want, add a frame and door. If they tend to slip at all, add two strands of barbed wire between each layer to keep them from shifting.

I'll add to this important topic with some pics of how I rebuilt the roof of an existing root cellar this past summer. I suppose that technically it's not really a root cellar as it has a concrete floor instead of dirt ...
I think that this cellar was constructed in the early 1950's. It has a very unique arched roof truss system that I've not seen before. The roof had rotted out and earth was beginning to fall into the cellar itself. This is where the water well pressure tank is located, so I wanted to be sure it was well protected from cold weather this coming winter (temps down to 0 degrees F with lots of wind).

The trusses were constructed from 1" x 4" x 10' planks. I found some spruce planks, but not enough for the job so filled in the rest with hemlock/fir planks. To conform to the arch radius the planks needed to be steamed.

Pic of the steamer set-up:

The propane cookstove heated a conventional pressure cooker. A heat-resistant tube was connected to a fitting tapped into a 10' length of ABS pipe capped at both ends. One end had an adjustable valve and the other a tiny drilled hole to release steam pressure build-up. I could "cook" two planks at a time for about an 90 minutes. When they were pulled out, they were quite hot and thoroughly wet. They then bent easily into the forming jig:

The climate is dry in Ritzville (about 30% RH) and the planks took a "set" in the two hours it took to cook the next set. After each pair of planks set into an initial arc, they were transferred to the truss which was aligned with an original truss to get the correct lengths and arch:

Each truss consisted of four arced planks retained in a bracket. As weight is applied to the wood arches (by covering with soil), the arch tries to flatten, driving the ends outward. The bracket prevents this and the whole truss system ends up with the wood planks in compression while the bracket is in tension:

Once all the trusses were rebuilt (I initially thought I'd only need to rebuild five, but in the end did all ten of them) they were spaced across the concrete block walls of the cellar and blocking was installed to maintain spacing

Then three layers of 3/8ths inch plywood were applied, giving a finished roof thickness of 1 1/8 inches. The original roof was two layers of 3/4" x 12" planks. I think the plywood roof will be considerably stronger due to the cross-laminated layers:

Then applied two layers of roofing felt, two layers of rolled asphalt roofing, and two layers of 6 mil plastic sheeting:

Finally, the cellar roof was recovered with earth. The concrete block building adjacent to the cellar contains a 3000 gallon in-ground water cistern. It's currently fed from the well, but my next project is to feed it from a roof water collection system.

We dug ours out of the hill behind the house. We don't use it a lot for roots - mostly for bottling (or canning) we've done and of course for wine. We can also hang a carcass in here until it's ready for butchering. A very useful space which saves on refrigeration.

I'm delighted with how ours has turned out. The gloriette was an afterthought, the temperature wasn't low enough because we didn't dig deep enough to have a good thickness of earth on top so we needed more shade. The climbers have started to cover the gloriette and it's nice and cool in there now.

Because I want mine to serve multiple purposes including an earth berm, and because part of our property is in an 'inundation zone' for flood water I really want mine to sit at the current ground level. I'm swaying towards an old shipping container as these are also water-tight and can hold a lot of weight on top.

My questions now are, About how deep does the earth layer need to be on top to get the right sort of temperatures inside? and Is it OK to be airtight or do I need to have some sort of venting?

So I've been pondering this idea of a shipping container on flat property that has a high water table (prevents digging down to bury the thing) ... how to thermally insulate/isolate it so that it will act like a root cellar.

So, what if you set your shipping container aligned north-south (to minimize solar gain), stacked straw bales all around and on top of it, then finished by stacking earthbags around and on top of that? It would give you the benefits of an instant cellar (container), thermal insulation from the straw bales, and fireproofing/thermal mass from the earthbags. It would end up being rather tall and the straw bales /earthbags might need to be "terraced" some for stability. I think it would be effective, although heavy in manual labor. Kind of a cross between and Earthship, a strawbale house, and an earthbag building!

That sounds like a plan! Using straw bales makes a lot of sense and I like the sound of the sandbags. That system would probably be a lot easier than trying to use truckloads of soil. Although I'm not averse to using truck loads of soil as a nice tall hill on the corner would do wonders for the wind, dust and car lights!

Thanks guys, I've got some good ideas to go on with. I'll keep you posted on my plans...

I've learned a lot from this thread ! Gandalf, those pictures are amazing... and HardworkingHippy... I've been your friend on Flickr for a bit now, and anytime anybody asks me about drying meat / storing, bottling, preserving... I "always" send them links to your photos. They are absolutely brilliant. My personal favorites are the corn harvesting pictures

Grahame, you mentioned that what lead you to thinking root cellar was a noisy corner. I'm also in the middle of suburbia, and while not on a corner, have an extremely noisy street right in front of our house. We were lucky enough that the old houses owner planted tons of natives out front, but the sound and exhaust still comes through, and high rates.

It probably wouldn't be a good place for a root cellar (it's the lowest point of our property, and faces a main street)... but, if you have any suggestions on good noise and carbon monoxide blocking species, I'd love to hear !

For thermal and noise insulation, you could try getting an old refrigerated shipping container with a U/S compressor to keep the cost down, i have seen containers in the ground before (not always on purpose!) and they will rust if the paint is not 100% - asphalt paint might help but dunno.
Does any one know if CO2 build up is a problem if these containers are not opened up regularly - maybe lots of homebrew or a damp unsealed floor with some organics in the soil?